The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be embodiments of the invention.
Scientists may gain insights into fundamental principles and understanding of materials through particle accelerator experiments. In these experiments, the velocity of a first group of particles may be increased in a magnetic field and made to collide with an object or second group of particles accelerated and directed to collide with the first group. Sensors may be used to observe collision artifacts resulting from the collisions. Collision artifacts may typically be present for very short periods of time. The duration of collision artifacts may define an observation period of interest. In some applications, collision artifacts may be available for a few nanoseconds. In some experiments, one or a small set of sensors may be used to detect collision artifacts. In other experiments, a large number of sensors may be used to simultaneously observe collision artifacts. The number of sensors that may be used in experiments may number in the tens, hundreds, thousands, or even hundreds of thousands. In many applications, accurate timing measurements of collisions and collision artifacts are critical measured parameters. In some applications, the desired relative timing accuracy, that is the desired relative timing between collisions and collision artifacts may be under 100 picoseconds. In some applications, the desired relative timing accuracy may be under 20 picoseconds. In some applications, the desired relative timing accuracy may be under one picosecond. In future applications, the desired relative timing accuracy may be on the order of femtoseconds. In future applications, the desired relative timing accuracy may be less than one femtosecond. In order to accurately capture the signals received from the sensors, very high sampling rates are used in the data acquisition electronics. In some applications, the sampling rate may be hundreds of megahertz. In some applications, the sampling rate may be gigahertz. For example, in an application, the sampling rate may be one-gigahertz. In another application, the sampling rate may be ten-gigahertz. In another application, the sampling rate may exceed ten-gigahertz.
There may be other existing and emerging applications where the time arrival of events may be detected by sensors and accurately translated into the digital domain by data acquisition electronics. An example of such as system is Lidar. Lidar is an acronym which stands for Light Detection and Ranging. In a Lidar system, a Lidar device may include a light source, a light detector, and measurement electronics. In an application, the light source may be a laser. One or more pulses of light may be emitted by the laser. Light emitted from the laser may be directed in a specific direction. When the pulse of emitted laser light hits a remote object, it may reflect off the object and a portion of the emitted laser light may return to the Lidar device as reflected laser light. The reflected laser light may be received by the light detector and processed by the support electronics. The roundtrip time duration from the instant the light is transmitted from the light source as transmitted light, to the instant the reflected light is received by the light detector may be measured by the measurement electronics. Based on the roundtrip time duration, the system may calculate the distance from the Lidar device to the remote object. The maximum roundtrip time duration may be limited by the distance limit between the Lidar device and the remote device. If the distance between the Lidar device and a remote object exceeds a distance limit, the object may not be identified. For some applications, the maximum roundtrip time duration may be on the order of microseconds. In an application, the maximum roundtrip time duration may be six microseconds. In an application, the maximum roundtrip time duration may be less than six microseconds. In another application, the maximum roundtrip time duration may be greater than six microseconds. In the application of Lidar, the relative timing accuracy may translate into a distance measurement accuracy between the Lidar device and the remote object. A relative timing accuracy of 1 nanosecond may translate to a distance measurement accuracy of approximately 0.3 meters.
Some implementations of Lidar utilize time-to-digital converters which may have a simple implementation utilizing a comparator and a counter. Other implementations may utilize an analog-to-digital converter and matched filtering which may be less sensitive to noise and the well-known problem of range walk error. However, due to the large amount of data that needs to be handled using analog-to-digital conversion, system designers often choose systems utilizing time-to-digital converters for simplicity. If the use of analog-to-digital converter-based designs can be made convenient, their use may become more prevalent due to the potential advantages in system robustness and accuracy.
To summarize, there are existing and emerging applications where data acquisition electronics with sample rates in the hundreds of megahertz to the gigahertz range, time events with a signal duration of interest as low as a few nanoseconds for collider experiments, observation periods up through microseconds for applications such as Lidar, and timing accuracy in the range of tens of picoseconds or less. Analog-to-digital converter resolutions may be between the range of six-bits to ten bits. In some applications, analog-to-digital converter resolutions fewer than six bits may be used. In other applications, analog-to-digital converter resolutions greater than ten bits may be used. The data acquisition system may provide: a. Digitized data—active portions of the signal may be converted to digital representation with moderate resolution and high sample rate; and b. Timing data—data to enable the identification of the position of a signal occurrence in time relative to a timing reference.
Architecting the data acquisition architecture to key in on portions of data that may contain data of interest and ignore data that may not contain data of interest may result in significant reduction in implementation complexity, peak current, power management, and power distribution requirements. The results may facilitate ease of use and reduce overall system cost.